The present disclosure relates generally to vehicle chassis control systems and, more particularly, to a method for synchronizing data utilized by redundant, closed-loop feedback control systems implemented in distributed vehicle chassis systems.
Chassis control systems such as, for example, electronically controlled brakes and steering, typically rely on feedback control methods to provide desired system performance and stability. Such systems utilize input sensors and feedback sensors to accomplish the feedback control, and are generally locally implemented within an individual electronic control unit (ECU). In this configuration, the sensors and associated computer signals are locally available at the ECU to perform the closed loop control. FIG. 1 is a block diagram illustrating an example of the general structure of a closed loop control system, which further includes a feedforward input coupled to the basic feedback structure. The diagram in FIG. 1 represents the most general, high-level description of a feedback/feedforward control system commonly implemented in automotive control systems.
Traditionally, these control systems have been included in vehicle architecture designs that are centralized in nature (i.e., designs that may be characterized as modular or self-contained). However, a growing motivation in the industry is to provide a distributed control architecture in which various control functions are distributed across multiple ECU's. In so doing, the level of vehicle subsystem integration is increased in an effort to reduce overall electrical system cost, improve packaging, reduce mass, increase availability, etc.
With certain vehicle systems, such as steer-by-wire and brake-by-wire, redundant control systems may be utilized to achieve a desired level of system fault tolerance. For example, multiple actuators, sensors and ECU's may be incorporated into the system to allow for continued operation of the brakes and/or steering in the event of a failure of some of the system components. Certain difficulties exist, however, in attempting to operate a redundant, closed loop feedback system in both a parallel and synchronous manner within the framework of a distributed control architecture.